ESP8266 Community Forum

- Thu Jul 21, 2016 2:22 pm #51206 Actually i have thought of a way around this, I will solder a wire off the gpio and then I can test this on a breadboard with different resistors, can fit in my pcb as well will get back once done.

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- Thu Jul 21, 2016 2:45 pm #51207

I can find no documentation anywhere that says to use a resistor, every example is a wire.

Hi, the idea of using a resistor with most GPIO's even if they connect back to the IC is to ensure that you don't overload the output.
The GPIOs on an ESP are rated at 12mA which equates to 3.3V / 0.012A = 275 Ohms.
You could have a case where you connect two GPIOs together for some reason (like in the PIR circuit), if when doing your development or during general use both are set as outputs. One is high and one is low, without the current limiting resistor one or both of the outputs would be damaged I tend to use 1K as the input impeadance of ESP's is about 100M so even if it forms a voltage divider the effect is negligable.
So =< 275 ohms, I would use a 1K.
EDIT: It has been pionted out that there is also a maximum value or it is not possable to pull RESET down to manualy reset for flashing etc. This is being considered at the moment and I will post back.

Last edited by Barnabybear on Fri Jul 22, 2016 3:36 am, edited 1 time in total.

- Thu Jul 21, 2016 2:56 pm #51208 Thanks for the explanation. That is exactly what I chose to test with However, I am having difficulties soldering this pin, think I have bricked one of the modules Any tips on the soldering part

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- Thu Jul 21, 2016 2:59 pm #51209 No not bricked but the solder amount on the GPIO has shrunk a lot. Any usefill tips on getting a wire soldered to it ?

Amazing selection of ESP8266 and ESP32 modules can be found here.